共查询到20条相似文献,搜索用时 15 毫秒
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Jincheol Park Hyungkeuk Lee Sanghoon Lee Bovik A.C. 《Multimedia, IEEE Transactions on》2009,11(6):1062-1071
To achieve seamless multimedia streaming services over wireless networks, it is important to overcome inter-cell interference (ICI), particularly in cell border regions. In this regard scalable video coding (SVC) has been actively studied due to its advantage of channel adaptation. We explore an optimal solution for maximizing the expected visual entropy over an orthogonal frequency division multiplexing (OFDM)-based broadband network from the perspective of cross-layer optimization. An optimization problem is parameterized by a set of source and channel parameters that are acquired along the user location over a multicell environment. A suboptimal solution is suggested using a greedy algorithm that allocates the radio resources to the scalable bitstreams as a function of their visual importance. The simulation results show that the greedy algorithm effectively resists ICI in the cell border region, while conventional nonscalable coding suffers severely because of ICI. 相似文献
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Minimum Energy Transmission Over a Wireless Channel With Deadline and Power Constraints 总被引:1,自引:0,他引:1
《Automatic Control, IEEE Transactions on》2009,54(12):2841-2852
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In this note, we study the problem of distributed control over communication channels, where a number of distributed stations collaborate to stabilize a linear system. We quantify the rate requirements and obtain optimal signaling, coding and control schemes for decentralized stabilizability in such multicontroller systems. We show that in the absence of a centralized decoder at the plant, there is in general a rate loss in decentralized systems as compared to a centralized system. This result is in contrast with the absence of rate loss in the stabilization of multisensor systems. Furthermore, there is rate loss even if explicit channels are available between the stations. We obtain the minimum data rates needed in terms of the open-loop system matrix and the connectivity graph of the decentralized system, and obtain the optimal signaling policies. We also present constructions leading to stability. In addition, we show that if there are dedicated channels connecting the controllers, rate requirements become more lenient, and as a result strong connectivity is not required for decentralized stabilizability. We determine the minimum number of such external channels leading to a stable system, in case strong connectivity is absent. 相似文献
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We consider the optimal control problem for the load of several communication channels defined by independent Markov jump processes. Implicit information on the state of a channel is available in the form of a flow of losses whose intensity is proportional to the controllable load of this channel. The optimized functionals take into account the total throughput of channels and energy costs for data transmission over a fixed interval of time. We obtain optimal filtering equations for joint estimation of channel states. We construct a locally optimal strategy that explicitly depends on the set of state estimates. 相似文献
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Nakagawa T. Ito K. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2008,38(2):461-469
Aged fossil-fired power plants are on the great increase in Japan, and the importance of preventive maintenance (PM) increases for their steady operations. A plant consists of a wide variety of mechanical and electrical components. Various kinds of severe failures inherent in these components and their occurrence probabilities are different. A system fails when the total suffered damage exceeds a peculiar level, i.e., these components have their peculiar damage levels. The PM plan should be established, considering such levels of plant components. In this paper, kinds of peculiar cumulative damage levels are considered, and a system fails when the total damage exceeds these damage levels. The PM is performed when the total damage exceeds the managerial one . The expected cost per unit time between maintenances is secured, and the optimal managerial level which minimizes it is analytically discussed. 相似文献
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Middleton R.H. Rojas A.J. Freudenberg J.S. Braslavsky J.H. 《Automatic Control, IEEE Transactions on》2009,54(1):163-167
Recent developments in information theory by Y.-H. Kim have established the feedback capacity of a first order moving average additive Gaussian noise channel. Separate developments in control theory have examined linear time invariant feedback control stabilization under signal to noise ratio (SNR) constraints, including colored noise channels. This note considers the particular case of a minimum phase plant with relative degree one and a single unstable pole at z=phi (with |phi| > 1) over a first order moving average Gaussian channel. SNR constrained stabilization in this case is possible precisely when the feedback capacity of the channel satisfies CFB ges log2 |phi|. Furthermore, using the results of Kim we show that there exist linear encoding and decoding schemes that achieve stabilization within the SNR constraint precisely when CFB ges log2 |phi|. 相似文献
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瑞利信道中双门限检测算法性能仿真及研究 总被引:1,自引:1,他引:1
研究无线网络通信,提高信道性能,改进检测方法,感知频谱环境是认知无线电的首要任务,如何在衰落信道中提高频谱的检测性能对现有认知无线电技术提出挑战.采用瑞利信道为典型信道,针对不同的协作感知方法展开研究,确定将一种双门限感知法植入瑞利信道,克服了唯一门限较难确定及系统开销大的问题.通过仿真,结果表明,双门限法与传统检测方法相比,不仅提高了检测概率,且减小了不必要的系统开销. 相似文献
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Consideration was given to the problems of error-free information transmission through an unreliable communication channel with allowance for duration of the arbitrarily distributed disturbing factor. It was assumed that the distribution functions of packet transmission time, inter-error duration, and time of elimination of the disturbing factor are arbitrary as well. The generalized probability of undistorted information transmission in a given time was obtained. The expectation of the time of error-free transmission was calculated, and its examination enabled determination of a rational strategy of information transmission. 相似文献
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基于流媒体的隐蔽通信可靠传输机制的研究 总被引:3,自引:0,他引:3
首先分析了原有流媒体隐蔽通信系统模型在传输机制上存在的问题.在此基础上改进了原有的传输方案,提出了一种新的基于流媒体的隐蔽通信的可靠传输机制,并进行实现和实际测试.实验结果表明,对于只有当载体满足一定条件时才可以嵌入的隐藏算法,新的传输机制也能保证可靠传输,性能较以前的方法也有长足的改善. 相似文献
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Automation and Remote Control - We consider the problem of optimizing the operation of a queuing system in which the number of working service channels can be changed in a controlled manner at... 相似文献
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《Automatic Control, IEEE Transactions on》2008,53(11):2633-2638
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The class of combinatorial optimization problems over polyhedral-spherical sets is considered. The results of theory of convex extensions are generalized to certain classes of functions defined on sphere-located and vertex-located sets. The original problem is equivalently formulated as a mathematical programming problem with convex both objective function and functional constraints. A numerical illustration and possible applications of the results to solving combinatorial optimization problems are given. 相似文献
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虚拟MIMO是一种克服无线多媒体传感器网络信道多径衰落和降低节点能耗的有效方法,但现有文献均假设信道状态信息未知或仅知道信道的统计特性,源节点则无法根据信道的实时信息动态调整传输策略。针对WMSNs信道特点,提出一种适用于WMSNs传输机制的信道盲估计方法以获得节点间信道信息进而确定传输策略,通过构造权值衰减联合决策函数,将节点间的信道盲估计问题转化为一个无约束优化问题,在此基础上设计了一种快速收敛的迭代算法以降低运算代价。该方法仅依赖小数据量就可正确估计出节点间信道,具有对抗信道时变特性的能力;理论推导与仿真表明该算法的收敛速度和运算量均能符合降低节点能耗的要求。 相似文献
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针对C~3I通信系统骨干网设计实用需求,文章重点对军用卫星通信信道传输损耗计算进行了研究。本文可对C~3I系统通信网总体设计技术提供参考。 相似文献
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《Journal of Parallel and Distributed Computing》2000,60(4):494-509
This paper discusses techniques for transmitting smoothed video more efficiently over a wireless network. The fluctuation of wireless channel conditions can add a significant amount of delay to video packets and cause them to miss their play-out time. If a video is smoothed, it is possible to selectively deliver packets delayed at the base-station to reduce the impact of the missing packets on video quality. In this paper, we present a simple yet effective packet selection algorithm which accomplishes this goal. This algorithm determines whether to transmit a packet based on channel conditions as well as the likelihood that higher priority layers in the rest of the video will be delivered on time. We introduce the concept of quality index to measure the performance of the algorithm. Results from trace-driven simulations show that the performance of the algorithm is close to optimal under a wide variety of channel conditions when the threshold is set between 0.7 and 0.9. 相似文献
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Valery A. Ugrinovskii Ian R. Petersen 《Mathematics of Control, Signals, and Systems (MCSS)》1999,12(1):1-23
We consider a linear-quadratic problem of minimax optimal control for stochastic uncertain control systems with output measurement.
The uncertainty in the system satisfies a stochastic integral quadratic constraint. To convert the constrained optimization
problem into an unconstrained one, a special S-procedure is applied. The resulting unconstrained game-type optimization problem is then converted into a risk-sensitive
stochastic control problem with an exponential-of-integral cost functional. This is achieved via a certain duality relation
between stochastic dynamic games and risk-sensitive stochastic control. The solution of the risk-sensitive stochastic control
problem in terms of a pair of differential matrix Riccati equations is then used to establish a minimax optimal control law
for the original uncertain system with uncertainty subject to the stochastic integral quadratic constraint.
Date received: May 13, 1997. Date revised: March 18, 1998. 相似文献